Dry transfer materials

ABSTRACT

A dry transfer material which includes a carrier sheet having a solvent-inert, substantially non-extensible, highly cross-linked polymeric surface. Indicia, such as letters or symbols, which form a film are printed on the surface and a dry elastomeric pressure sensitive adhesive extends over the indicia.

United States Patent 1191 Hochner 1 Nov. 12, 1974 [5 1 DRY TRANSFER MATERIALS 3,276,933 10/1966 Brant 161/406 T 3,298,850 1/1967 Reed et a1. 161/406 T [75] lnvmtor- Walter Hmhnei Arcadla 3,411,978 11/1968 Frottbach ct 211. 161 167 [73] Assignee: Avery Products Corporation, San 3,454,458 7/1969 Borregard 161/406 Marino, Calif. [22] Filed; 28, 1969 Primary Examiner--Wi1liam J. Van Balen [21] A l N 880 541 Attorney, Agent, or FirmChr1stie, Parker & Hale [52] us. c1 l6l/167, 117/31, 117/34, ABSTRACT [51] Int Cl 5 A dry transfer material which includes a carrier sheet [58] Fieid 167, having a solvent-inert, substantially non-extensible, {17/3 3 highly cross-linked polymeric surface. lndicia, such as letters or symbols, which form a film are printed on [56] References Cited the surface and a dry elastomeric pressure sensitive UNITED STATES PATENTS adhesive extends over the indicia. 3,065,120 11/1962 Avelzrr 161/406 T 9 Claims, 1 Drawing Figure 1 wee/2 F/LM wzy/z/wc 60/1 7 01/6 v DRY TRANSFER MATERIALS BACKGROUND OF THE 'INVENTION Dry transfer materials are widely used in the creation of designs, advertising media, and other art work which is produced by transferring to a receiving sheet individual indicium carried on a single transfer sheet to provide a desired combination of letters or symbols on the receiving sheet. In more recent years, the term dry transfer materials has been generally applied to those materials in which the indicia are adhered to the receiving sheet by a pressure sensitive adhesive that becomes adherent only upon applicationof substantial pressure. As a result, the transparent carrier sheet may be readily slid over the receiving surface to align a specific indicium in a desired position, whereupon transfer is effected by rubbing or burnishing the reverse side'of the carrier sheet in the vicinity of the indicium to be transferred.

Dry transfer materials of the kind described above are well known, and consist of a carriersheet, ink indicia in the form of symbols, letters, or designs printed on the carrier sheet, and a layer of pressure sensitive adhesive overlying the indicia and the unprinted portion of the carrier sheet. The pressure sensitive adhesive overlaps the indicia onto the carrier sheet and typically shears along the outline of theindicium to be transferred without accompanying transfer of the overlapping adhesive. Since, however, the transferring pressure is produced by rubbing or burnishing, stretching of many of the carriersheets heretofore used can occur as a result of the transferring operation. This produces undesirable consequences. For example, even relatively slight elongation of the carrier sheet can result in distortion of the ink indicia'as deposited on the receiving sheet. In larger size letters,actual breaking and cracking can result. Withsome highly extensible materials, such as certain grades of polyethylene, rubbing or burnishing exceeds the elongation point of the material and produces a permanent stretchfWhen this occurs, proper alignment of untransferred indicia on a semiused transfer sheet becomes difficult and timeconsuming.

STATEMENT OF THE INVENTION It has now been found that the above-described transfer difficultiespresent in prior art dry transfer materials can be obviated by combining a carrier sheetincluding a surface of certain properties with an adhesive and a printing medium which are selected so that their respective adhesions to the surface, while significantly different, do not depend upon solvent interaction between the surfaceand the adhesive or printing medium. The interrelated properties of the separate transfer elements enable use of a nonextensible surface since stretching plays no significant function in the transfer operation. Distortion-free transfer of indicia from a single transfer sheet can, as a result, be repetitively effected.

The dry transfer material of the present invention comprises a carrier sheet including a solvent-inert, substantially non-extensible, highly cross-linked polymeric film of high tensile strength.

In the presently preferred embodiment of the invention, the polymeric surface is obtained by applying a coating to a carrier film which does not necessarily have the required surface characteristics. The manner in which such a dry transfer material functions to provide distortion-free transfer of indicia will be more readily understood following a description of the desirable characteristics of the separate elements.

Polymeric Coating It is required that the surface to which the indicia and adhesive are applied be substantially non-extensible and insoluble in the solvents typically used in printing media and in adhesives. These characteristics are found in highly cross-linked or branched polymeric materials. Thermosetting polymers, such as polyvinylbutralmelamine, ureaformaldehyde, polyvinylformal-phenol, melamineepoxy, and thermosetting acrylics, are particularly useful. These may be used to provide the required surface by printing, spraying, dipping, or .coating a carrier film with the selectedjpolymeric material.

As stated above,the polymeric coating must be substantially non-extensible. By this is meant materials which have very low ultimate elongations. For example, the ultimate elongations of urea-formaldehyde and melamine-formaldehyde, whichare utilizable as polymeric coatings in this invention, are'0.5 to 1.0 and 0.6 percent, respectively,-(-measured by ASTM D 638). By way of comparison, the ultimate elongations of some materials used as prior art carrier sheets are 10 to percent for polystyrene, to percent for polyesters, and 225 to '500;percent'for medium density polyethylene (measured by ASTM D 882). The preferred polymeric coatings verge, therefore, on being brittle, that is, they tend to break or snap before any significant stretching or elongation occurs.

To be useful in' the dry transfer material of this invention, there'mustbe'noiappreciable interaction between the polymericcoatingand the solvents, diluents, or resins commonly'used in adhesives or in printing inks. This characteristic is found inhighly cross-linked polymeric coatings. For example, a variety of chemical compounds have been applied to the surface of a cured polyvinylbutral-melamine coating and permitted to evaporate. No'appreciable physical or chemical effect upon the surface'was produced. These compounds included mineral spirits, hexane, cyclohexane, solvent naphtha, toluene, trichloroethylene, carbon disulfide, chloroform, carbon tetrachloride, nitrobenzene, pxylene, ethylene dichloride, o-dichlorbenzene, methylene chloride, ethyl acetate, ethylene-glycol monomethyl ether, ethylene glycol monomethyl ether acetate, tetrahydrofuran, methyl ethyl ketone, acetone, methyl iso-butyl ketone, 1,4 dioxane, morpholine, methanol, ethanol,isopropanoLN-butyl alcohol, ethylene glycol, and diethylene .glycol ,monobutyl ether.

Since the incidia must be viewed from the-reverse side of the carrier sheet to position individual indicium for transfer to a receiving sheet, the'polymeric coating must-be transparent. Thepolymeric coatings discussed above have high clarityand can be provided with either a smooth or mattesurface as desired.

Indicia Theprintingzinks-must include ingredients which exhibit high tensile strength when cast as a film -to form indicia on-'the polymeric surface. Preferably,

the ink'base is a vinylchloride-vinyl acetate copolymer which forms a tough film. The polymer is preferably dissolved in a fairly high surfacetension solvent system,

the polymeric coating and the ingredients of the printing ink, the indicia are lightly adhered to the surface of the polymeric coating in the manner suggested by the adsorption theory of adhesion. For example, removal of a one-half inch strip of indicia formed from an ink as described above requires a force of the order of five grams, as tested in accordance with the standard 90 peel test.

Adhesive The adhesive must be one which does not adhere to a receiving surface at light pressure but will adhere upon application of significant pressure, e.g., 50 pounds per square inch. Additionally, however, it is required that the adherence of the adhesive to the polymeric coating be significantly greater than the adherence of the indicia to the coating. To this end, an adhesive base polymer which is a rubbery elastomer is selected and is dissolved in a fairly low surface tension solvent system. Such a combination is found, for example, by dissolving cis-polyisoprene in an aliphatic solvent. The solution can be made into a poor film-former by controlled addition of fillers or thermosetting resins or the like.

Since the adhesive solution is not a film-former and the solvent system tends to wet the polymeric coating, the stress concentration in the adhesive layer close to the interface between the layer and the polymeric surface of the coating is far less than that found in the ink film. Although, as in the case of the printing ink, there is no solvent interaction between the adhesive and the polymeric coating, the adherence of the adhesive to the coating is substantially greater than that of the ink film.

As compared to the force of five grams required with respect to the ink film, a force of one hundred grams is required, in accordance with the standard 90 peel test, t m esnehel n Strip. qf q lei/st From the description of the characteristics of the polymeric coating, adhesive layer, and indicia that has been given, it will be seen that a dry transfer material is provided which does not require stretching to effect transfer of indicia. Transfer can be effected by pressure distributed equally over the entire indicium to be transferred without localized pressure as is applied when stretching is required to free an indicium from a carrier sheet. Even if localized pressure is applied, the nonextensible characteristic of the polymeric coating prevents stretching of the operative elements of the dry transfer material. The prior problems of distortion and permanent stretching of semi-used sheets are thereby avoided.

BRIEF DESCRIPTION OF DRAWING The drawing is a cross-section of a preferred embodiment of a dry transfer material in accordance with the invention.

DETAILED DESCRIPTION OF INVENTION As shown in the drawing, a preferred embodiment of the invention includes a polymeric coating, preferably urea-formaldehyde or melamine-formaldehyde, coated upon a carrier film. Although the carrier film does not directly affect the mechanism of transfer, it should have good transparency and dimensional stability, and not be susceptible to solvent attack. The latter is desired to avoid either mechanical or chemical interaction between the polymeric coating and the carrier film.

Although the ultimate elongation of the carrier film need not be as low as that of the polymeric coating, it is desirable that the percent ultimate elongation of the carrier approach that of the polymeric coating. Forthis purpose, certain polyester films may be used. For example, there are commercially available polyester films which require 15,000 to 23,000 p.s.i. to produce an elongation of 5 percent. Other acceptable carrier films include transparent papers, such as glassine or parchment grades.

The polymeric coating is then printed with a printing ink having the surface tension and film-forming characteristics previously described. Inks based upon vinyl chloride-vinyl acetate resins or acrylic resins produce films of high tensile strength, e.g., 1,200 to 2,000 p.s.i., which readily peel from the coating. A coating of pressure sensitive adhesive having the characteristics already described is then applied over the indicia and the unprinted portion of the polymeric coating.

Pressure is then applied in the vicinity of the indicium to be transferred to adhere the indicium to the receiving surface. Since the indicium is relatively lightly adhered to the polymeric coating as compared to the adherence of the adhesive to the coating, the indicium may be readily pulled from the polymeric coating by the adherence of the adhesive to the receiving surface.

Although the adhesive overlaps the indicium, it shears along the outline of the indicium so that little or no halo of adhesive is transferred. The process as described above can then be repeated to transfer another letter or symbol in alignment with the first transferred letter or symbol. Because the polymeric coating is nonextensible, the transferred indicium is not distorted by stretching nor does any permanent elongation of the coating occur.

In the table below, examples of formulations of polymeric coatings satisfactorily utilized in making dry transfer materials in accordance with the invention are given in parts by weight:

The following are examples of printing ink formulations, all in parts by weight, which have been satisfactorily used with the polymeric coatings described above and the adhesive formulations described below:

lnk Example No. 1

Vinyl Chloride-Vinyl Acetate Copolymer 50 Dioctyl Phthalate 2O Cyclohexanone 240 Ultramarine Blue Carbon Black 5 lnk Example No. 2

Vinyl Chloride-Vinyl Acetate Copolymer 100 Epoxidized Soya l0 Cyclohexanone 200 lsophorone Carbon Black 20 Ink Example No.3

' Vinyl Chloride-Vinyl Acetate Copolymer 100 Diisooctyl Phthalate 30 lsophorone 150 Cyclohexanone 150 Carbon Black 15 Ink Exam le No.4

n-butyl Methacrylate l00 Chlorinated bi-phenyl Plasticizer Carbon Black 25(5) Cyclohexanone The following are examples of adhesive formulations which have been satisfactorily used in making dry transfer materials in combination with the polymeric coating and ink formulations described above:

Adhesive Example No. l

Styrene-Butadiene Rubber lOO Thermoplastic Polystyrene Resin 200 H dro enated Wood Rosin 100 Sili a iller 20 Antioxidant 3 Mineral Spirits 500 Aromatic 100 Sql enttliumble Qil Co.) 590 dwamm Pale Crepe Rubber 100 Polyterpene Resin 75 Paraffin Wax 150 Antioxidant v 5 -Continued Silica Filler Naphtha 400 Mineral Spirits 400 Adhesive Example No. 3

Polyisobutylene l00 Polyterpene Resin I50 Hydrogenated Rosin Ester 50 Silica Filler 30 Antioxidant 2 Mineral Spirits 800 Toluene 200 Dry transfer materials were made utilizing combinations of the above described coatings, adhesives, and inks. Indicia were transferred by placing the dry transfer sheet in contact with a suitable receiving sheet between the platens of a hydraulic press and applying a pressure in excess of 50 p.s.i. Examination of the polymeric coating surface after transfer of indicia showed no visual change. Examination of the surface by multiple internal reflectance spectroscopy showed no chemical change in the surface.

Dry transfer materials made in accordance with the present invention provide a product of highly improved appearance and durability. Convenient transfer of indicia can be achieved under a variety of conditions without adverse effects upon the indicia as transferred or the sheet from which the transfer is made.

I claim:

1. A dry transfer material comprising a carrier sheet including a solvent-inert, substantially non-extensible, highly cross-linked polymeric surface, indicia forming a film printed on said surface, and a dry elastomeric pressure sensitive adhesive extending over the indicia and the polymeric surface.

2. Material in accordance with claim 1 wherein the indicia form a film of high tensile strength.

3. Materialin accordance with claim 1 wherein the adherence of the adhesive to the polymeric surface is substantially greater than the adherence of the indicia to the polymeric surface.

4. Material in accordance with claim 1 wherein the polymeric surface is a thermosetting resin.

5. A dry transfer materialcomprising a carrier sheet, a solvent-inert, substantially non-extensible, highly crosslinked polymeric coating on one surface of the carrier sheet, indicia forming a film printed on said coating, and a dry elastomeric pressure sensitive adhesive extending over the indicia and the coating.

6. Material in accordance with claim 5 wherein the indicia form a film of high tensile strength.

7. Material in accordance with claim 5 wherein the indicia are formed from a film-forming polymer dissolved in a high surface tension solvent.

8. Material in accordance with claim 7 wherein the film-forming polymer is a vinyl chloride-vinyl acetate copolymer.

9. Material in accordance with claim 5 wherein the adherence of the adhesive to the polymeric coating is substantially greater than the adherence of the indicia to the polymeric coating.

Po-ww v "UNITED STATES PATENT OFFICE .s/ w o P9 CERTIFICATE OF CORRECTION Patent No- 3.347.725 D te liovmberll, 197

Inventor) Walter L. Hochner It is certified that error appears in the'above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 5, line 13, "8" should read .8

Signed and sealed this 21st day of January 1975.

QSEAL) Attest:

MCCOY M. GIBSON JR. C. MARSHALL DANN Attesting Officer Commissioner of Patents 

1. A DRY TRANSFER MATERIAL COMPRISING A CARRIER SHEET INCLUDING A SOLVENT-INERT, SUBSTANTIALLY NON-EXTENSIBLE, HIGHLY CROSSLINKED POLYMERIC SURFACE, INDICIA FORMING A FILM PRINTED ON SAID SURFACE, AND A DRY ELASTOMERIC PRESSURE SENSITIVE ADHESIVE EXTENDING OVER THE INDICA AND THE POLYMERIC SURFACE.
 2. Material in accordance with claim 1 wherein the indicia form a film of high tensile strength.
 3. Material in accordance with claim 1 wherein the adherence of the adhesive to the polymeric surface is substantially greater than the adherence of the indicia to the polymeric surface.
 4. Material in accordance with claim 1 wherein the polymeric surface is a thermosetting resin.
 5. A dry transfer material comprising a carrier sheet, a solvent-inert, substantially non-extensible, highly crosslinked polymeric coating on one surface of the carrier sheet, indicia forming a film printed on said coating, and a dry elastomeric pressure sensitive adhesive extending over the indicia and the coating.
 6. Material in accordance with claim 5 wherein the indicia form a film of high tensile strength.
 7. Material in accordance with claim 5 wherein the indicia are formed from a film-forming polymer dissolved in a high surface tension solvent.
 8. Material in accordance with claim 7 wherein the film-forming polymer is a vinyl chloride-vinyl acetate copolymer.
 9. Material in accordance with claim 5 wherein the adherence of the adhesive to the polymeric coating is substantially greater than the adherence of the indicia to the polymeric coating. 